Smith-Lemli-Opitz syndrome (SLOS) is a rare genetic condition affecting multiple body systems. Signs and symptoms may include characteristic facial features, small head size, growth and developmental delays, and intellectual and behavioral problems. Individuals with SLOS have abnormally low levels of cholesterol in their blood and high levels of a chemical known as 7-dehydrocholestrol. The severity of symptoms varies from individual to individual. Many babies have feeding difficulties and growth issues. Some are born with heart, kidney, and adrenal problems. Most people with SLOS have some degree of intellectual and behavioral difficulties. This condition is caused by genetic changes (DNA variants) in the DHCR7 gene and is inherited in an autosomal recessive pattern. This condition is diagnosed based on the features and laboratory and genetic testing.